Forming dome-shaped mesh



OCt. 26, 1965 s, BROWN FORMING DOME-SHAPED MESH Filed NOV. 21, 1963 INVENTCR SILAS A. BROWN BY W 1% ATTORNEY United States Patent C) 3,213,658 FORMING DOME-SHAPED MESH Silas Arthur Brown, Lake Elmo, Minn, assignor to Buckbee-Mears Company, St. Paul, Minn, a corporation of Minnesota Filed Nov. 21, 1963, Ser. No. 325,374 11 Claims. (Cl. 7247) This invention is directed toward forming thin fiat metallic discs of precision articles into a dome-shaped configuration. Articles formed according to the teachings of this invention may have a dome depth ranging up to and including a hemisphere. In particular, the invention is concerned with forming thin flat metallic discs, containing precisely shaped and arranged elongated metallic filaments, into a dome-shaped configuration Without causing distortion, breaking or any substantial change in the orientation of the filaments. Throughout the following specification and claims, it should be understood that the term mesh is used in a generic sense to include thin sheets of material containing precision patterns formed therein, with the patterns essentially comprising elongated filaments of the material with inter-posed aperture areas in a predetermined array.

Heretofore, the principal difliculty encountered in forming metallic mesh into a dome-shaped configuration has been the tendency of the filaments to distort, break or otherwise shift out of their precisely defined orientation. This has been especially true in the case of form ing deep-domed mesh approaching that of a hemisphere configuration and even more so when attempting to dome mesh made of certain metallic materials. It is the primary object of this invention to provide method and apparatus for producing precision metallic mesh articles in a domeshaped configuration.

A further object of this invention is to achieve the foregoing objective using a variety of metals for the mesh material.

Still another object of this invention is to achieve the foregoing objectives with a dome-depth ranging up to and including a hemisphere.

Yet another object is to achieve the foregoing objectives in an economical manner.

For illustrative purposes only, the following detailed description will be concerned with a mesh pattern comprising two orthogonal groups of elongated metallic filaments extending across the annular area of a thin ring of the same metallic material. This type of mesh is illustrated in FIGURE 1 and will be subsequently described in greater detail. The application of the teachings of this invention to mesh of various patterns, e.g., thin discs of metal incorporating arcuate and radial filaments such as the cross-hairs of a reticle, will become apparent during the course of the following description.

In the practice of this invention, a thin fiat metallic mesh disc is nested in a co-extensive disc of a different metallic material with the filaments of the former seated in corresponding grooves in the latter. The nested mesh is then pressed into the desired dome-shaped configuration while the nesting disc retains the filaments of the mesh in their respective precisely aligned orientation. As a further extension of the novel features of this invention, the nested mesh is covered with another disc of metallic material before doming. As the forming pressure is applied onto the covering disc, the latter retains the filaments in snug seating engagement with the respective grooves in the nesting disc. As a further feature of this invention, sufficient forming pressure is applied so that the mesh remains between the nest and the covering layer and is thereby protected against misuse during subsequent handling. The protective layers can be readily stripped away from the mesh and discarded when desired.

3,213,658 Patented Oct. 26, 1965 'ice These and other features of this invention will become apparent during the course of the following detailed description, with reference to the accompanying drawings in which:

FIGURE 1 is a partial fragmentary view of an apparatus capable of forming mesh into a dome-shaped configuration according to the method of this invention.

FIGURE 2 is a detailed sectional view of an embodi ment of this invention illustrating a fixture or jig for forming mesh into the dome-shaped configuration;

FIGURE 3 is a partial sectional view illustrating the cooperative engagement of the nest and the mesh.

With reference to FIG. 1, there is shown a thin disc 13 containing metallic mesh 10, formed by two coplanar orthogonal groups of elongated metallic filaments 11 extending across the annular area defined by a thin ring 12 of the same metal. In a typical case, the mesh disc 13 comprising the mesh 10 and the supporting ring 12 is formed by electroforming or etching. Techniques and processes for fabricating mesh discs of this nature are well known in the art. Briefly, in the etching process the desired pattern is photoprinted on a suitably prepared surface of the metallic disc and the metal is selectively removed by an appropriate etchant. In electroforming, the metal is electrolytically deposited in the desired pattern which has been previously defined by photoprinting. For illustrative purposes, the disc may be made of molybdenum in the order of .0017 inch thick and .712 inch outer diameter. The intersecting filaments may have a line width in the order of .0015 inch to define a plurality of interposed apertures and provide a mesh in the order of 30 lines per inch.

Underlying the mesh disc 13 is a brass nesting disc 14 having the same outer diameter as the mesh disc but eight to ten times thicker, preferably. The brass disc 14 contains a ring portion 15 corresponding to ring 12 of mesh disc 13 and a plurality of elongated grooves 16, respectively corresponding to the mesh filaments 11, formed on the top surface of the brass disc. The nesting pattern in disc 14 is the complement of the mesh pattern, and can be formed, similar to the mesh pattern in disc 13, by suitable photoprinting and etching processes. The mesh disc 13 is placed on the nesting disc 14, with the filaments of the former seated in respectively corresponding grooves in the latter. When in this cooperative arrangement, the apertures in the mesh contain corresponding raised land areas 17 of the nesting disc 14. The cooperative engagement of the two discs is more clearly shown in FIG. 3 which illustrates filaments 11 of the mesh disc 13 nesting in corresponding grooves on the upper surface of the nesting disc 14. The nested mesh can then be formed into the desired dome shape by being pressed into a dome-defining die cavity 18 in the face of a cylindrical die block 19 or can be press-shaped in any other convenient manner. The malleability characteristic of the brass nesting disc results in the pattern-defining grooves and land areas remaining substantially unchanged and in their desired alignment when the nesting disc is subjected to the forming pressure. This, in turn, prevents the mesh filaments from altering in line width or orientation.

In order to ensure that the mesh filaments are retained in their respective seating engagements with the grooves in the nesting disc 14, a further brass disc 20 having dimensions substantially similar to the nesting disc, overlays the nested mesh disc prior to doming. The forming pressure is applied to the covering disc 20 so that the filaments are forcibly retained in their corresponding grooves in the nesting disc.

Although the forming pressure can be applied to the mesh in a variety of manners, one effective mode is illustrated in FIG. 1. A solid steel sphere having a curvature corresponding to the dome-defining cavity 18 is forced downward, by a convenient means such as a press (not shown), on a cylindrical section of lead 22 which is placed on top of the covering brass disc 20. The forming pressure is transferred from a steel ball 21, which aids in shaping the mesh as it is forced into the die cavity 18, uniformly through the lead onto the mesh sandwiched between the covering disc 20 and nesting disc 14. The pressure is uniformly distributed over the entire area of the discs as they are pressed into the cavity. Preferably, the forming pressure is applied gradually to prevent rupturing of the mesh filaments which might occur as a result of a sudden impacting force. The layer of lead further ensures against this force being applied too suddenly. It has been found preferable to have the layer of lead made up of a group of lead discs to facilitate removal of the lead after the article has been formed, as will be described subsequently with reference to the apparatus of FIG. 2.

As pointed out previously, the applied forming pressure causes the three discs, 20, 13 and 14, to adhere together so that after the mesh has been formed, it is encased in protective layers. Until the mesh requires further processing, this condition can be maintained so that the mesh is protected against mishandling or the like. When necessary, the encasing layers can be readily stripped away from the mesh and discarded.

FIG. 2 is a sectioned vertical view of a doming fixture or jig. The sandwich arrangement of the nesting disc 23, the mesh disc 24 and the covering disc 25, covers the hemispheric die cavity 26 contained in the top facing surface of the solid steel cylindrical die block 27. A lower guide block 28 is slidably mounted on and coaxial with the die block 27, and containsa bore' including a cylindrical section 29 and a frusto-conical section 30, with the diameter of the former being only slightly larger than the diameter of the discs to retain the discs centrally aligned with the die cavity. A cylindrical piece of lead 31 rests on top of the sandwiched discs to a height above the frusto-conical portion of the bore of the lower guide block. Seated on top of the lead is a solid steel ball 32 which is loosely contained in a suitably contoured section of a bore in the upper cylindrical guide block 33 which covers the top of the lower guide block 28. Slidably extending upward from contact with the steel ball 32 in the cylindrical portion of the bore in the upper guide block 33 is an elongated cylindrical steel rod 32 which protrudes above the top of guide block 33 with the protruding length surrounded by a helical spring 35. With the fixture assembled as illustrated in FIG. 2, a downward force is exerted on spring 35, and the steel rod 34, by means not shown, to apply pressure downward onto the steel ball 32. As the downward force is gradually increased, the pressure applied through the lead 31 on the sandwiched discs forces them into the die cavity 26. As the steel ball pushes down on the lead, the latter tends to deform by spreading outward and upward and is allowed to do so only to a limited degree until it strikes the down-facing portion of the upper guide block 33 in the area adjacent the bore. The compression force on spring 35 prevents the lead from forcing the upper guide block 33 up and away from the lower guide block 28 so that the forming pressure is continuously and uniformly applied throughout the lead on the sandwiched discs.

As stated earlier, the piece of lead is preferably made up of a group of lead discs so that when the lead is deformed, it is less likely to adhere to the bore surface, and subsequent removal of the lead is facilitated. The fixture is made up of separable sections to facilitate disassembly and removalof the formed articles. After the article has been formed to the contour of the die cavity, the pressure is released and the two guide block sections are slipped up and away from the die block 27, and the dome-shaped mesh with its protective covering layers is removed from the cavity. The fixture may then be re-assembled as previously described to dome another article. For each doming operation, new lead, nesting and covering discs are required. The domed mesh can then be retained in its encased condition and the cover ing layers subsequently removed when required for further processing of the mesh.

What is claimed is:

1. A method for forming thin, fiat metallic mesh into a dome shape, comprising the steps of:

(a) placing a thin flat disc of metallic mesh into cooperative nesting relationship with grooves defining the complementary pattern of the mesh formed on a surface of a flat disc of a different metal so that the areas of said latter disc between the grooves extend at least part way into the open areas between the filaments of said mesh; and

(b) applying pressure to the nested discs to form them into a dome shape while being held securely in said nesting relationship.

2. A method for forming thin, flat metallic mesh into a dome shape, comprising the steps of:

(a) placing a thin fiat disc of metallic mesh into cooperative nesting relationship with a disc of a different metal containing grooves defining a complementary mesh pattern so that the open areas between the mesh filaments are at least partly filled by the corresponding areas between the grooves of the latter disc;

(b) laying the nested mesh disc flat over a dome-defining die cavity; and

(c) applying pressure on the nested disc forcing it into the cavity for forming to the contour thereof and for securely holding the disc in said nesting relationship.

3. The method as described in claim 2 wherein the different metal is characterized by greater malleability than the mesh metal.

4. A method for forming thin, flat metallic mesh into domes shape, comprising the steps of:

(a) placing a thin, flat disc of the metallic mesh into cooperative nesting relationship with a flat disc of a different metal characterized by greater malleability than the mesh metal containing a nesting pattern of grooves complementary to the mesh pattern so that the open areas between the mesh filaments are at least partly filled by corresponding areas between grooves of said latter disc;

(b) covering the nested mesh disc with a smooth, flat disc of said difierent metal;

(c) placing the covered nested disc over a dome-defining die cavity; and

(d) applying pressure on said covering disc for forcing the covered nested disc into the cavity until formed to the contour thereof and for securely holding the mesh in said nesting relationship while being so formed.

5. A method for forming dome-shaped metallic mesh,

comprising the steps of:

(a) forming a thin flat disc of metal mesh comprising a plurality of elongated metallic filaments with open areas therebetween;

(b) forming on a surface of a flat disc of a different metal which is particularly characterized by greater malleability than the mesh metal a plurality of grooves defining a complementary pattern of said mesh filaments;

(c) laying the mesh on said latter disc with the filaments of the former nesting in respectively corresponding grooves in the latter so that areas between grooves of the latter at least partly fill the open areas in the former; and

(d) applying pressure on the nested mesh discs to form them into a dome shape while securely holding them together in said relationship.

6. A method for forming dome-shaped metallic mesh, comprising the steps of:

(a) forming a thin flat disc of metal mesh comprising a plurality of elongated metallic filaments with open areas therebetween;

(b) forming on a surface of a flat disc of a different metal particularly characterized by greater malleability than the mesh metal a plurality of grooves defining a complementary pattern of said mesh filaments;

(c) laying the mesh over said latter disc with the filaments of the former nesting in respectively corresponding grooves in the latter so that the open areas of said mesh are at least partly filled by corresponding areas of said latter disc;

(d) covering the nested mesh disc with a substantially smooth surfaced flat disc of said different metal; and

(e) pressing on the covering disc to securely hold the so-arranged disc in the aforesaid engagement while forming them into a dome shape.

7. Apparatus for forming metallic mesh into a dome shape, comprising: a die cavity defining the desired dome configuration; a fiat disc of metal containing a plurality of grooves on a surface in a pattern corresponding to the mesh pattern adapted to receive the mesh with its filaments in nesting relationship in said grooves; and means for pressing said disc with the mesh nested therein into said cavity for forming to the dome-defining contour thereof.

8. Apparatus for forming metallic mesh into a dome shape configuration, comprising: a die block containing a partial-spherical cavity; a first flat metallic disc containing a plurality of grooves formed on one surface thereof adapted to receive the mesh filaments in nesting engagement in said grooves; a substantially smooth flat metal disc for overlaying the mesh when nested in the grooves in said first disc; and means for pressing said discs with the mesh therebetween into the die cavity.

9. Apparatus for forming metallic mesh into a dome shape configuration, comprising: a die block face containing a dome-defining cavity; a first flat metal disc removably covering said cavity, said disc having on its opposite surface a plurality of grooves adapted to receive corresponding metallic filaments of the mesh in flat nesting engagement; a substantially smooth fiat metal disc for removably covering the mesh when it is nested in said first disc; and means for applying pressure onto the covered nested mesh to form it to the cavity contour.

10. The method as described in claim 4 wherein the pressure is applied in step (d) by pressing down on a deformable metal which overlays the covered nested disc with an arcuate member of solid construction having a contour corresponding to that of the die cavity, said deformable metal acting to apply the downward pressure relatively uniformly in all directions onto the covered nested disc thereby forming it to the contour of the die cavity while the mesh is being held securely in the nesting relationship whereby the mesh filaments retain their relative placements within the mesh.

11. Apparatus as in claim 9 wherein said pressure applying means includes a layer of relatively soft deformable metal overlaying said smooth, flat metal disc and a solid metal ball contoured to conform at least in part to the die cavity for applying pressure downward on the deformable metal so that the latter applies the pressure uniformly on the covered nested metal mesh whereby the mesh is retained in its nesting engagement while being formed to the contour of the die cavity.

References Cited by the Examiner UNITED STATES PATENTS 2,960,763 11/60 Reichl 29423 3,132,420 5/64 Pompa 29423 FOREIGN PATENTS 180,489 6/22 Great Britain.

CHARLES W. LANHAM, Primary Examiner. 

1. A METHOD FOR FORMING THIN, FLAT METALLIC MESH INTO A DOME SHAPE, COMPRISING THE STEPS OF: (A) PLACING A THIN FLAT DISC OF METALLIC MESH INTO COOPERATIVE NESTING RELATIONSHIP WITH GROOVES DEFINING THE COMPLEMENTARY PATTERN OF THE MESH FORMED ON A SURFACE OF A FLAT DISC OF A DIFFERENT METAL SO THAT THE AREAS OF SAID LATTER DISC BETWEEN THE GROOVES EXTEND AT LEAST PART WAY INTO THE OPEN AREAS BETWEEN THE FILAMENTS OF SAID MESH; AND (B) APPLYING PRESSURE TO THE NESTED DISCS TO FORM THEM INTO A DOME SHAPE WHILE BEING HELD SECURELY IN SAID NESTING RELATIONSHIP. 